I have been using the 12oz Zojirushi stainless steel travel mug for about 18 months – I use it daily and I absolutely love it. I tried the ever-popular Timolino (several models actually) and I was not really satisfied / not impressed. The Zojirushi beats them hands down IMHO. I love them so much, I bought a 16oz and I just picked up another 12oz recently.
They keep things hot all day long and do not “contaminate” the flavor at all. Fill it and drink out of it for hours knowing my tea’s temperature is just as I like it and then I brew and refill it again. If I want to drink out of a small cup, I use it as a teapot because I do not enjoy drinking lukewarm tea. Highly recommend to all.